;(function(){
  var store = {},
    win = window,
    doc = win.document,
    localStorageName = 'localStorage',
    namespace = '__storejs__',
    storage

  store.disabled = false
  store.set = function(key, value) {}
  store.get = function(key) {}
  store.remove = function(key) {}
  store.clear = function() {}
  store.transact = function(key, defaultVal, transactionFn) {
    var val = store.get(key)
    if (transactionFn == null) {
      transactionFn = defaultVal
      defaultVal = null
    }
    if (typeof val == 'undefined') { val = defaultVal || {} }
    transactionFn(val)
    store.set(key, val)
  }
  store.getAll = function() {}

  store.serialize = function(value) {
    return JSON.stringify(value)
  }
  store.deserialize = function(value) {
    if (typeof value != 'string') { return undefined }
    try { return JSON.parse(value) }
    catch(e) { return value || undefined }
  }

  // Functions to encapsulate questionable FireFox 3.6.13 behavior
  // when about.config::dom.storage.enabled === false
  // See https://github.com/marcuswestin/store.js/issues#issue/13
  function isLocalStorageNameSupported() {
    try { return (localStorageName in win && win[localStorageName]) }
    catch(err) { return false }
  }

  if (isLocalStorageNameSupported()) {
    storage = win[localStorageName]
    store.set = function(key, val) {
      if (val === undefined) { return store.remove(key) }
      storage.setItem(key, store.serialize(val))
      return val
    }
    store.get = function(key) { return store.deserialize(storage.getItem(key)) }
    store.remove = function(key) { storage.removeItem(key) }
    store.clear = function() { storage.clear() }
    store.getAll = function() {
      var ret = {}
      for (var i=0; i<storage.length; ++i) {
        var key = storage.key(i)
        ret[key] = store.get(key)
      }
      return ret
    }
  } else if (doc.documentElement.addBehavior) {
    var storageOwner,
      storageContainer
    // Since #userData storage applies only to specific paths, we need to
    // somehow link our data to a specific path.  We choose /favicon.ico
    // as a pretty safe option, since all browsers already make a request to
    // this URL anyway and being a 404 will not hurt us here.  We wrap an
    // iframe pointing to the favicon in an ActiveXObject(htmlfile) object
    // (see: http://msdn.microsoft.com/en-us/library/aa752574(v=VS.85).aspx)
    // since the iframe access rules appear to allow direct access and
    // manipulation of the document element, even for a 404 page.  This
    // document can be used instead of the current document (which would
    // have been limited to the current path) to perform #userData storage.
    try {
      storageContainer = new ActiveXObject('htmlfile')
      storageContainer.open()
      storageContainer.write('<s' + 'cript>document.w=window</s' + 'cript><iframe src="/favicon.ico"></iframe>')
      storageContainer.close()
      storageOwner = storageContainer.w.frames[0].document
      storage = storageOwner.createElement('div')
    } catch(e) {
      // somehow ActiveXObject instantiation failed (perhaps some special
      // security settings or otherwse), fall back to per-path storage
      storage = doc.createElement('div')
      storageOwner = doc.body
    }
    function withIEStorage(storeFunction) {
      return function() {
        var args = Array.prototype.slice.call(arguments, 0)
        args.unshift(storage)
        // See http://msdn.microsoft.com/en-us/library/ms531081(v=VS.85).aspx
        // and http://msdn.microsoft.com/en-us/library/ms531424(v=VS.85).aspx
        storageOwner.appendChild(storage)
        storage.addBehavior('#default#userData')
        storage.load(localStorageName)
        var result = storeFunction.apply(store, args)
        storageOwner.removeChild(storage)
        return result
      }
    }

    // In IE7, keys may not contain special chars. See all of https://github.com/marcuswestin/store.js/issues/40
    var forbiddenCharsRegex = new RegExp("[!\"#$%&'()*+,/\\\\:;<=>?@[\\]^`{|}~]", "g")
    function ieKeyFix(key) {
      return key.replace(forbiddenCharsRegex, '___')
    }
    store.set = withIEStorage(function(storage, key, val) {
      key = ieKeyFix(key)
      if (val === undefined) { return store.remove(key) }
      storage.setAttribute(key, store.serialize(val))
      storage.save(localStorageName)
      return val
    })
    store.get = withIEStorage(function(storage, key) {
      key = ieKeyFix(key)
      return store.deserialize(storage.getAttribute(key))
    })
    store.remove = withIEStorage(function(storage, key) {
      key = ieKeyFix(key)
      storage.removeAttribute(key)
      storage.save(localStorageName)
    })
    store.clear = withIEStorage(function(storage) {
      var attributes = storage.XMLDocument.documentElement.attributes
      storage.load(localStorageName)
      for (var i=0, attr; attr=attributes[i]; i++) {
        storage.removeAttribute(attr.name)
      }
      storage.save(localStorageName)
    })
    store.getAll = withIEStorage(function(storage) {
      var attributes = storage.XMLDocument.documentElement.attributes
      var ret = {}
      for (var i=0, attr; attr=attributes[i]; ++i) {
        var key = ieKeyFix(attr.name)
        ret[attr.name] = store.deserialize(storage.getAttribute(key))
      }
      return ret
    })
  }

  try {
    store.set(namespace, namespace)
    if (store.get(namespace) != namespace) { store.disabled = true }
    store.remove(namespace)
  } catch(e) {
    store.disabled = true
  }
  store.enabled = !store.disabled
  if (typeof module != 'undefined' && module.exports) { module.exports = store }
  else if (typeof define === 'function' && define.amd) { define(store) }
  else { this.store = store }
})();
